Project Summary Meaningful social connection??i.e., close relationships marked by social support?? depends upon the ability to effectively value social stimuli (e.g., close others relative to strangers). Close relationships provide a key context for both making decisions with shared consequences (e.g., sharing an investment) and safety in the face of adversity (e.g., stressful life events), and links between social relationships and decision-making have been associated with enhanced signaling in reward-related neural circuitry. Critically, lacking close relationships and social support is associated with social isolation, poor physical health outcomes and increased likelihood for mental health conditions such as depression and substance abuse. In spite of these established links, it is unknown how social support and close relationships: 1) influence the value placed on social experiences; 2) choices involving shared risky consequences; and 3) buffer negative effects of adverse social interactions. Addressing these gaps in the decision and social/affective neuroscience literatures has important implications for understanding alterations in the mechanisms underlying atypical socioemotional and decision processes in depression and substance abuse disorders. Using behavioral, computational and functional neuroimaging (fMRI) approaches in healthy young adults (ages 18-35), we will investigate how meaningful social connection and social abilities (e.g., self-esteem, autistic traits) influence the relative value of social (vs. non-social) experiences, neurocomputational signals underlying risk evaluation in social contexts and ways in which negative social interactions shape subsequent preferences for social experiences. Across three aims, participants will perform a series of tasks combining social manipulations with economic decision-making tasks allowing for the assessment of value computation. We predict that participants? valuation of social over non-social experiences will correlate positively with levels of social support and overall general social abilities, and that these behavioral patterns will be reflected in increased recruitment of and connectivity with reward-related neural circuitry (Aim 1). We also predict that decision-making in social versus non-social contexts (i.e., involving friends, strangers vs. involving the self) will be associated with increased avoidance of risk and increased sensitivity to social losses in reward-related circuitry; we further expect these behavioral and neural patterns to correlate positively with social support and social closeness with a partner (Aim 2). Lastly, we predict that negative social experiences (i.e., social exclusion) will reduce the value placed on social over non-social experiences, but that social support will buffer this effect (Aim 3). Taken together, this proposal will delineate mechanisms by which social support and close relationships shape value- based choices, inspiring future work in clinical samples afflicted with depression and substance use disorders. Importantly, this project will provide cutting-edge interdisciplinary training for undergraduates in the PI?s laboratory in behavioral, computational and neuroimaging methods, fulfilling the goals of the R15 mechanism.